Bare electronic chips typically need to be packaged in a package that provides an electric circuit between each electrical connection of the chip and an external connector such as a pin or a ball extending from the package to external circuitry such as a printed circuit board. In designing rules for manufacturing chips having different geometries (such as smaller features of devices such as wiring traces or transistors) it is costly to design, test, and qualify additional features. Chips that run at extremely high frequencies, e.g., upwards of 40 gigahertz, also have rule constraints as to the type, thickness, spacing, and layout of traces and signal pads required to provide adequate signal capability. Further, such chips typically need to be run at very low voltages (e.g., about one volt) and very high currents (e.g., one hundred amps), which must be provided in order to achieve the desired high frequencies.
The circuit side of the chip typically provides pads that are connected to the chip's packaging using, for example, solder-ball connections.
Typical high-performance packaging can include a ball-grid array package having relatively large balls (e.g., in a ball-grid array) with relatively large spacings on one side of the package for external connections, and small closely spaced pads on the same side or the opposite side for connections to a ball-grid-array set of solder-ball connections to the electronic chip (such as a processor, communications, or memory chip).
Wirebonding equipment and manufacturing processes are often less expensive than tight-tolerance solder ball equipment and manufacturing processes, particularly for devices that can accommodate the signal characteristics provided by wirebond connections.
A package typically has a non-conductive substrate (such as a plastic film or layer) with conductive traces (wires) on or in a surface of the substrate. Either solder ball connections or wirebond connects a chip to the package. Some packages include multiple chips, such as one or more logic or processor chips, one or more communications chips (such as for a cell phone or wireless LAN), and/or one or more memory chips, such as a FLASH-type reprogrammable non-volatile memory. Optionally, a cover or encapsulant is used to enclose the chip or chips.
What is needed is a simple, inexpensive, reliable method and apparatus to fabricate packaging for electronic chips, so that solder ball connections or wirebond connections can be used.